[BIOCHEM LAB MIDTERMS] TO2

Molisch test

What is the general test for all carbohydrates?

alpha-naphthol in 95% ethanol

What is the reagent used in Molisch test?

PURPLE ring

What is the positive result for Molisch test?

mono and disaccharides

These are crystalline, water-soluble, sparingly soluble in organic solvents (ex: sugar)

polysaccharides

these are non crystalline and water insoluble; glycosidic linkage (ex: starches and cellulose)

Furfural

What is formed when pentoses undergo dehydration?

Hydroxymethylfurfural

What is formed when hexoses undergo dehydration?

Schiff test

What test detects the presence of aldehyde group or aldoses?

purple solution

What is the positive result for Schiff test?

PURPLE/MAGENTA

What color indicates presence of free aldehyde in Schiff test?

REFRIGERATOR

How should Schiff reagent be stored?

Tollen test

What test uses silver nitrate in ammonia water as oxidizing agent?

phenylhydrazine test

test of reducing sugars with a result of the formation of yellow crystal

ammoniacal silver nitrate

What is the composition of Tollen reagent?

oxidation and reduction

2 reactions of monosaccharides

GLUCONIC ACID

what does oxidation of aldehyde and glucose produce

carboxylate anion

the aldehyde group or an aldose is oxidized under basic conditions to a?

aldonic acid

the oxidation product of an aldose is called?

glycosides

reactions with methyl alcohol forming acetals and ketals is called?

galactonic acid

What does oxidation of aldehyde and galactose produce

silver mirror

What is the positive result for Tollen test?

Tollen gluconic acid

What acid is produced when glucose is oxidized in Tollen test?

Fehling test

What test uses copper ion as oxidizing agent to detect reducing sugars?

hydrated cuso4 solution

What is the composition of Fehling A solution?

potassium sodium tartrate tetrahydrate or rochelle salt in naoh solution

What is the composition of Fehling B solution?

brick-red ppt

What is the positive result for Fehling test?

1mg

How much glucose can Fehling test detect?

Benedict test

What test uses copper sulfate to detect reducing sugars?

green to brick red ppt.

What is the positive result for Benedict test?

Nylander test

What test uses bismuth hydroxide nitrate as oxidizing agent?

black ppt.

What is the positive result for Nylander test?

Picric acid test

What test uses picric acid to detect reducing sugars?

2,4,6-trinitrophenol (TNP)

What is the chemical name of picric acid?

TOXIC

Is picric acid toxic or non-toxic?

MAHOGANY RED SOLUTION

What is the positive result for Picric acid test?

glucose, lactose

What sugars give positive result in Picric acid test?

sucrose

What sugar gives negative result in Picric acid test?

Moore test

What test uses strong NaOH as reagent for reducing sugars?

strong NaOH

What is the reagent used in Moore test?

Golden brown soln

What is the positive result for Moore test?

none

Does Moore test have a reduced product?

D-Glucitol

What sugar alcohol is produced from D-glucose?

D-Sorbitol

What is another name for D-Glucitol?

a-1, b-2

What type of glycosidic linkage does sucrose have?

Invert sugar

What is the mixture of glucose and fructose produced from sucrose hydrolysis?

Sucrose

What is the sweetest disaccharide?

germinating Stains

Where is maltose commonly found?

hydrolysis

sucrose needs sucraze enzyme through this process for easy conversion to produce invert sugar

2 glucose

Maltose composition

glucose + galactose

What monosaccharides make up lactose?

milk, yogurt, ice cream

Where is lactose commonly found?

glucose + fructose

sucrose composition

f

t/f Sucrose gives positive result in all redox tests.

T

All monosaccharides are reducing sugars. T/F

t

true or false Sucrose has a glycosidic bond involving both anomeric carbons.

f

Invert sugar is a mixture of glucose and galactose. t/f